scholarly journals Differential CD4+ T-Lymphocyte Apoptosis and Bystander T-Cell Activation in Rhesus Macaques and Sooty Mangabeys during Acute Simian Immunodeficiency Virus Infection

2008 ◽  
Vol 83 (2) ◽  
pp. 572-583 ◽  
Author(s):  
Mareike Meythaler ◽  
Amanda Martinot ◽  
Zichun Wang ◽  
Sarah Pryputniewicz ◽  
Melissa Kasheta ◽  
...  

ABSTRACT In contrast to pathogenic lentiviral infections, chronic simian immunodeficiency virus (SIV) infection in its natural host is characterized by a lack of increased immune activation and apoptosis. To determine whether these differences are species specific and predicted by the early host response to SIV in primary infection, we longitudinally examined T-lymphocyte apoptosis, immune activation, and the SIV-specific cellular immune response in experimentally infected rhesus macaques (RM) and sooty mangabeys (SM) with controlled or uncontrolled SIV infection. SIVsmE041, a primary SIVsm isolate, reproduced set-point viremia levels of natural SIV infection in SM but was controlled in RM, while SIVmac239 replicated to high levels in RM. Following SIV infection, increased CD8+ T-lymphocyte apoptosis, temporally coinciding with onset of SIV-specific cellular immunity, and elevated plasma Th1 cytokine and gamma interferon-induced chemokine levels were common to both SM and RM. Different from SM, SIV-infected RM showed a significantly higher frequency of peripheral blood activated CD8+ T lymphocytes despite comparable magnitude of the SIV-specific gamma interferon enzyme-linked immunospot response. Furthermore, an increase in CD4+ and CD4−CD8− T-lymphocyte apoptosis and plasma tumor necrosis factor-related apoptosis-inducing ligand were observed only in RM and occurred in both controlled SIVsmE041 and uncontrolled SIVmac239 infection. These data suggest that the “excess” activated T lymphocytes in RM soon after SIV infection are predominantly of non-virus-specific bystander origin. Thus, species-specific differences in the early innate immune response appear to be an important factor contributing to differential immune activation in natural and nonnatural hosts of SIV infection.

2006 ◽  
Vol 80 (6) ◽  
pp. 2771-2783 ◽  
Author(s):  
Zichun Wang ◽  
Benjamin Metcalf ◽  
Ruy M. Ribeiro ◽  
Harold McClure ◽  
Amitinder Kaur

ABSTRACT Sooty mangabeys are a natural host of simian immunodeficiency virus (SIV) that remain asymptomatic and do not exhibit increased immune activation or increased T-lymphocyte turnover despite sustained high levels of SIV viremia. In this study we asked whether an altered immune response to SIV contributes to the lack of immunopathology in sooty mangabeys as opposed to species with pathogenic lentivirus infection. SIV-specific cellular immune responses were investigated in a cohort of 25 sooty mangabeys with natural SIV infection. Gamma interferon (IFN-γ) enzyme-linked immunospot (ELISPOT) assay responses targeting a median of four SIV proteins were detected in all 25 mangabeys and were comparable in magnitude to those of 13 rhesus macaques infected with SIVmac251 for more than 6 months. As with rhesus macaques, Th2 ELISPOT responses to SIV were absent or >10-fold lower than the IFN-γ ELISPOT response to the same SIV protein. The SIV-specific ELISPOT response was predominantly mediated by CD8+ T lymphocytes; the frequency of circulating SIV-specific CD8+ T lymphocytes ranged between 0.11% and 3.26% in 13 mangabeys. Functionally, the SIV-specific CD8+ T lymphocytes were cytotoxic; secreted IFN-γ, tumor necrosis factor alpha, and macrophage inflammatory protein 1β; and had an activated effector phenotype. Although there was a trend toward higher frequencies of SIV-specific CD8+ T lymphocytes in mangabeys with lower viral loads, a significant inverse correlation between SIV viremia and SIV-specific cellular immunity was not detected. The consistent detection of Th1-type SIV-specific cellular immune responses in naturally infected sooty mangabeys suggests that immune attenuation is neither a feature of nor a requirement for maintenance of nonpathogenic SIV infection in its natural host.


2007 ◽  
Vol 82 (3) ◽  
pp. 1084-1093 ◽  
Author(s):  
Amitinder Kaur ◽  
Michele Di Mascio ◽  
Amy Barabasz ◽  
Michael Rosenzweig ◽  
Harold M. McClure ◽  
...  

ABSTRACT Increased lymphocyte turnover is a hallmark of pathogenic lentiviral infection. To investigate perturbations in lymphocyte dynamics in natural hosts with nonpathogenic simian immunodeficiency virus (SIV) infection, the nucleoside analog bromodeoxyuridine (BrdU) was administered to six naturally SIV-infected and five SIV-negative sooty mangabeys. As a measure of lymphocyte turnover, we estimated the mean death rate by fitting a mathematical model to the fraction of BrdU-labeled cells during a 2-week labeling and a median 10-week delabeling period. Despite significantly lower total T- and B-lymphocyte counts in SIV-infected sooty mangabeys than in SIV-negative mangabeys, the turnover rate of B lymphocytes and CD4+ and CD8+ T lymphocytes was not increased in the SIV-infected animals. A small, rapidly proliferating CD45RA+ memory subset and a large, slower-proliferating CD45RA− central memory subset of CD4+ T lymphocytes identified in the peripheral blood of sooty mangabeys also did not show evidence of increased turnover in the context of SIV infection. Independently of SIV infection, the turnover of CD4+ T lymphocytes in sooty mangabeys was significantly higher (P < 0.01) than that of CD8+ T lymphocytes, a finding hitherto not reported in rhesus macaques or humans. The absence of aberrant T-lymphocyte turnover along with an inherently high rate of CD4+ T-lymphocyte turnover may help to preserve the pool of central memory CD4+ T lymphocytes in viremic SIV-infected sooty mangabeys and protect against progression to AIDS.


1998 ◽  
Vol 72 (12) ◽  
pp. 9597-9611 ◽  
Author(s):  
Amitinder Kaur ◽  
Robert M. Grant ◽  
Robert E. Means ◽  
Harold McClure ◽  
Mark Feinberg ◽  
...  

ABSTRACT Sooty mangabeys naturally infected with simian immunodeficiency virus (SIV) do not develop immunodeficiency despite the presence of viral loads of 105 to 107 RNA copies/ml. To investigate the basis of apathogenic SIV infection in sooty mangabeys, three sooty mangabeys and three rhesus macaques were inoculated intravenously with SIVmac239 and evaluated longitudinally for 1 year. SIVmac239 infection of sooty mangabeys resulted in 2- to 4-log-lower viral loads than in macaques and did not reproduce the high viral loads observed in natural SIVsmm infection. During acute SIV infection, polyclonal cytotoxic T-lymphocyte (CTL) activity coincident with decline in peak plasma viremia was observed in both macaques and mangabeys; 8 to 20 weeks later, CTL activity declined in the macaques but was sustained and broadly directed in the mangabeys. Neutralizing antibodies to SIVmac239 were detected in the macaques but not the mangabeys. Differences in expression of CD38 on CD8+ T lymphocytes or in the percentage of naive phenotype T cells expressing CD45RA and CD62L-selection did not correlate with development of AIDS in rhesus macaques. In macaques, the proportion of CD4+ T lymphocytes expressing CD25 declined during SIV infection, while in mangabeys, CD25-expressing CD4+T lymphocytes increased. Longitudinal evaluation of cytokine secretion by flow cytometric analysis of unstimulated lymphocytes revealed elevation of interleukin-2 and gamma interferon in a macaque and only interleukin-10 in a concurrently infected mangabey during acute SIV infection. Differences in host responses following experimental SIVmac239 infection may be associated with the divergent outcome in sooty mangabeys and rhesus macaques.


2007 ◽  
Vol 81 (15) ◽  
pp. 8009-8015 ◽  
Author(s):  
Yue Sun ◽  
Sallie R. Permar ◽  
Adam P. Buzby ◽  
Norman L. Letvin

ABSTRACT It has long been appreciated that CD4+ T lymphocytes are dysfunctional in human immunodeficiency virus (HIV)/simian immunodeficiency virus (SIV)-infected individuals, and it has recently been shown that HIV/SIV infections are associated with a dramatic early destruction of memory CD4+ T lymphocytes. However, the relative contributions of CD4+ T-lymphocyte dysfunction and loss to immune dysregulation during primary HIV/SIV infection have not been fully elucidated. In the current study, we evaluated CD4+ T lymphocytes and their functional repertoire during primary SIVmac251 infection in rhesus monkeys. We show that the extent of loss of memory CD4+ T lymphocytes and staphylococcal enterotoxin B-stimulated cytokine production by total CD4+ T lymphocytes during primary SIVmac251 infection is tightly linked in a cohort of six rhesus monkeys to set point plasma viral RNA levels, with greater loss and dysfunction being associated with higher steady-state viral replication. Moreover, in exploring the mechanism underlying this phenomenon, we demonstrate that the loss of functional CD4+ T lymphocytes during primary SIVmac251 infection is associated with both a selective depletion of memory CD4+ T cells and a loss of the functional capacity of the memory CD4+ T lymphocytes that escape viral destruction.


2018 ◽  
Vol 92 (9) ◽  
Author(s):  
Diane Carnathan ◽  
Benton Lawson ◽  
Joana Yu ◽  
Kalpana Patel ◽  
James M. Billingsley ◽  
...  

ABSTRACT Pathogenic human immunodeficiency virus (HIV)/simian immunodeficiency virus (SIV) infection of humans and rhesus macaques (RMs) induces persistently high production of type I interferon (IFN-I), which is thought to contribute to disease progression. To elucidate the specific role of interferon alpha (IFN-α) in SIV pathogenesis, 12 RMs were treated prior to intravenous (i.v.) SIV mac239 infection with a high or a low dose of an antibody (AGS-009) that neutralizes most IFN-α subtypes and were compared with six mock-infused, SIV-infected controls. Plasma viremia was measured postinfection to assess the effect of IFN-α blockade on virus replication, and peripheral blood and lymphoid tissue samples were analyzed by immunophenotypic staining. Consistent with the known antiviral effect of IFN-I, high-dose AGS-009 treatment induced a modest increase in acute-phase viral loads versus controls. Four out of 6 RMs receiving a high dose of AGS-009 also experienced an early decline in CD4 + T cell counts that was associated with progression to AIDS. Interestingly, 50% of the animals treated with AGS-009 (6/12) developed AIDS within 1 year of infection compared with 17% (1/6) of untreated controls. Finally, blockade of IFN-α decreased the levels of activated CD4 + and CD8 + T cells, as well as B cells, as measured by PD-1 and/or Ki67 expression. The lower levels of activated lymphocytes in IFN-α-blockaded animals supports the hypothesis that IFN-α signaling contributes to lymphocyte activation during SIV infection and suggests that this signaling pathway is involved in controlling virus replication during acute infection. The potential anti-inflammatory effect of IFN-α blockade should be explored as a strategy to reduce immune activation in HIV-infected individuals. IMPORTANCE Interferon alpha (IFN-α) is a member of a family of molecules (type I interferons) that prevent or limit virus infections in mammals. However, IFN-α production may contribute to the chronic immune activation that is thought to be the primary cause of immune decline and AIDS in HIV-infected patients. The study presented here attempts to understand the contribution of IFN-α to the natural history and progression of SIV infection of rhesus macaques, the primary nonhuman primate model system for testing hypotheses about HIV infection in humans. Here, we show that blockade of IFN-α action promotes lower chronic immune activation but higher early viral loads, with a trend toward faster disease progression. This study has significant implications for new treatments designed to impact the type I interferon system.


2008 ◽  
Vol 82 (6) ◽  
pp. 3139-3146 ◽  
Author(s):  
M. Quinn DeGottardi ◽  
Anke Specht ◽  
Benjamin Metcalf ◽  
Amitinder Kaur ◽  
Frank Kirchhoff ◽  
...  

ABSTRACT Human immunodeficiency virus type 1 (HIV-1) Nef downregulates HLA-A and -B molecules, but not HLA-C or -E molecules, based on amino acid differences in their cytoplasmic domains to simultaneously evade cytotoxic T lymphocyte (CTL) and natural killer cell surveillance. Rhesus macaques and sooty mangabeys express orthologues of HLA-A, -B, and -E, but not HLA-C, and many of these molecules have unique amino acid differences in their cytoplasmic tails. We found that these differences also resulted in differential downregulation by primary simian immunodeficiency virus (SIV) SIVsmm/mac and HIV-2 Nef alleles. Thus, selective major histocompatibility complex class I downregulation is a conserved mechanism of immune evasion for pathogenic SIV infection of rhesus macaques and nonpathogenic SIV infection of sooty mangabeys.


2000 ◽  
Vol 74 (3) ◽  
pp. 1209-1223 ◽  
Author(s):  
Lisa A. Chakrabarti ◽  
Sharon R. Lewin ◽  
Linqi Zhang ◽  
Agegnehu Gettie ◽  
Amara Luckay ◽  
...  

ABSTRACT Sooty mangabeys naturally infected with simian immunodeficiency virus (SIV) remain healthy though they harbor viral loads comparable to those in rhesus macaques that progress to AIDS. To assess the immunologic basis of disease resistance in mangabeys, we compared the effect of SIV infection on T-cell regeneration in both monkey species. Measurement of the proliferation marker Ki-67 by flow cytometry showed that mangabeys harbored proliferating T cells at a level of 3 to 4% in peripheral blood irrespective of their infection status. In contrast, rhesus macaques demonstrated a naturally high fraction of proliferating T cells (7%) that increased two- to threefold following SIV infection. Ki-67+ T cells were predominantly CD45RA−, indicating increased proliferation of memory cells in macaques. Quantitation of an episomal DNA product of T-cell receptor α rearrangement (termed α1 circle) showed that the concentration of recent thymic emigrants in blood decreased with age over a 2-log unit range in both monkey species, consistent with age-related thymic involution. SIV infection caused a limited decrease of α1 circle numbers in mangabeys as well as in macaques. Dilution of α1 circles by T-cell proliferation likely contributed to this decrease, since α1 circle numbers and Ki-67+ fractions correlated negatively. These findings are compatible with immune exhaustion mediated by abnormal T-cell proliferation, rather than with early thymic failure, in SIV-infected macaques. Normal T-cell turnover in SIV-infected mangabeys provides an explanation for the long-term maintenance of a functional immune system in these hosts.


2000 ◽  
Vol 74 (18) ◽  
pp. 8413-8424 ◽  
Author(s):  
Amitinder Kaur ◽  
Corrina L. Hale ◽  
Saroja Ramanujan ◽  
Rakesh K. Jain ◽  
R. Paul Johnson

ABSTRACT Although lymphocyte turnover in chronic human immunodeficiency virus and simian immunodeficiency virus (SIV) infection has been extensively studied, there is little information on turnover in acute infection. We carried out a prospective kinetic analysis of lymphocyte proliferation in 13 rhesus macaques inoculated with pathogenic SIV. A short-lived dramatic increase in circulating Ki-67+lymphocytes observed at 1 to 4 weeks was temporally related to the onset of SIV replication. A 5- to 10-fold increase in Ki-67+ CD8+ T lymphocytes and a 2- to 3-fold increase in Ki-67+ CD3− CD8+natural killer cells accounted for >85% of proliferating lymphocytes at peak proliferation. In contrast, there was little change in the percentage of Ki-67+ CD4+ T lymphocytes during acute infection, although transient increases in Ki-67−and Ki-67+ CD4+ T lymphocytes expressing CD69, Fas, and HLA-DR were observed. A two- to fourfold decline in CD4+ T lymphocytes expressing CD25 and CD69 was seen later in SIV infection. The majority of Ki-67+ CD8+ T lymphocytes were phenotypically CD45RA−CD49dhi Fashi CD25−CD69− CD28− HLA-DR− and persisted at levels twofold above baseline 6 months after SIV infection. Increased CD8+ T-lymphocyte proliferation was associated with cell expansion, paralleled the onset of SIV-specific cytotoxic T-lymphocyte activity, and had an oligoclonal component. Thus, divergent patterns of proliferation and activation are exhibited by CD4+ and CD8+ T lymphocytes in early SIV infection and may determine how these cells are differentially affected in AIDS.


2005 ◽  
Vol 79 (21) ◽  
pp. 13759-13768 ◽  
Author(s):  
Candice C. Clay ◽  
Denise S. Rodrigues ◽  
Danielle J. Harvey ◽  
Christian M. Leutenegger ◽  
Ursula Esser

ABSTRACT To define the possible impact of T-lymphocyte trafficking parameters on simian immunodeficiency virus (SIV) pathogenesis, we examined migratory profiles of carboxyfluorescein diacetate succinimidyl ester (CFSE)-labeled T lymphocytes in acutely SIVmac251-infected and uninfected macaques within 48 h after autologous transfer. Despite significant upregulation of homeostatic chemokine CCL19/macrophage inflammatory protein 3β and proinflammatory chemokine CXCL9/monokine induced by gamma interferon in secondary lymphoid tissue in SIV infection, no differences in CFSE+ T-lymphocyte frequencies or cell compartmentalization in lymph nodes were identified between animal groups. By contrast, a higher frequency of CFSE+ T lymphocytes in the small intestine was detected in acute SIV infection. This result correlated with increased numbers of gut CD4 T lymphocytes expressing chemokine receptors CCR9, CCR7, and CXCR3 and high levels of their respective chemokine ligands in the small intestine. The changes in trafficking parameters in SIV-infected macaques occurred concomitantly with acute gut CD4 T-lymphocyte depletion. Here, we present the first in vivo T-lymphocyte trafficking study in SIV infection and a novel approach to delineate T-lymphocyte recruitment into tissues in the nonhuman primate animal model for AIDS. Such studies are likely to provide unique insights into T-lymphocyte sequestration in distinct tissue compartments and possible mechanisms of CD4 T-lymphocyte depletion and immune dysfunction in simian AIDS.


2019 ◽  
Author(s):  
RM Bochart ◽  
G Tharp ◽  
S Jean ◽  
AA Upadhyay ◽  
MM Crane ◽  
...  

AbstractSooty mangabeys (SMs) are a natural host species of simian immunodeficiency virus (SIV) and avoid acquired immune deficiency syndrome (AIDS) despite persistently high viral loads, making them a pivotal research model for HIV pathogenesis. Unlike pathogenic SIV infection of macaque species, or HIV infection of humans, SIV-infected SMs maintain gastrointestinal barrier integrity. Here, we characterize the gastrointestinal bacterial microbiota of SIV-infected and uninfected SMs and perform a comparative analysis of diet-matched, rhesus macaques (RM). We assessed the fecal microbiome in fifty SM and thirty RM in total, and conducted analyses of the effect of SIV-status, species, and housing. When examining indoor-outdoor and indoor-only housing in our SM cohorts, biodiversity reduction and mild phylogenetic taxonomic perturbances were present. No statistically relevant differences were seen for biodiversity richness and evenness, or phylogenetic taxonomic communities between SIV negative and positive SM cohorts. In contrast, with pathogenic early chronic SIV infections in RM a trend of alpha diversity loss and increase of beta diversity and few phyla taxonomic communities differed. Lastly, we observed lower levels of pathobiont bacterial communities in SIV-uninfected SMs relative to RMs. These data suggest that the pre-existing bacterial community structure may contribute to the divergent phenotype between SIV natural hosts and pathogenic macaque species.ImportanceHuman immunodeficiency virus remains a global concern. The sooty mangabey (SM) monkey is an important biomedical research model for understanding HIV pathogenesis due to its ability to avoid AIDS disease progression despite high viremia. In people living with HIV, gastrointestinal dysbiosis towards enrichment of pathobiont communities has been frequently reported. In this study we characterized the fecal microbiota of a primate non-pathogenic SIV host, the SM, and made direct comparisons to a pathogenic SIV host species, the rhesus macaque. We observed that SMs exhibit stability of the microbiota community into chronic SIV infection, which contrasts with SIV-infected rhesus macaques, in which we observed bacterial community divergence relative to uninfected animals. Collectively, our observation of stabilization of beneficent taxa in the mucosa of AIDS-resistant primates suggests that therapeutic strategies to enrich these communities may have potential for ameliorating the gastrointestinal inflammation in people living with HIV.


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